Nailable steel floor channel with anti-skid surface

ABSTRACT

A steel floor construction for freight hauling vehicles includes a plurality of elongated floor planking members arranged in side-by-side relation to provide a load bearing floor with a nailing groove between adjacent planking members. Each plank includes a downwardly open channel member having a relatively wide central web supported along its edges by integrally formed downwardly extending flanges, with the web being reinforced along its length by an upwardly directed generally U-shaped member welded to its bottom surface and having a pattern of anti-skid projections die-formed on and project upwardly from its top surface. The channels are progressively roll formed from a continuous length of strip steel by passing the strip through a series of forming roll pairs. A pair of die rolls are employed between two adjacent sets of forming rolls, with the die rolls being driven together and cooperating to form the anti-skid projections by a cold forming process after the sheet has been partially formed into this channel shape by passing through a plurality of the sets of forming rolls. The U-shaped reinforcing member is welded to the strip after the anti-skid projections are formed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a nailable steel flooring for freight handlingvehicles, and more particularly to nailable steel floor planking membershaving an improved anti-skid load bearing surface and to a method ofmanufacturing such planking members.

2. Description of the Prior Art

Freight handling vehicles such as trucks and rail cars, hereinaftergenerally referred to as cars or rail cars, are known in which the loadsupporting floor is constructed of transversly extending steel plankingmembers supported on longitudinally extending beams or girders. Theplanking members have conventionally been of a generally channel shapedconstruction with the central web of the channel forming the loadbearing surface and the side flanges extending downwardly and beingsupported on the girders. The side flanges are generally of complexshape and may include inwardly directed terminal portions which engagethe girders to support the floor structure. The downwardly extendingportions of the side flanges are normally of compound-curveconfiguration and include spacer members for engaging the side flangesof adjacent planking members to provide a nailing groove for securingarticles to the floors to prevent shifting during hauling. Thecooperating compound-curved side flanges of adjacent planking membersare of complementary nature to provide a substantially uniform spacingin the nailing grooves. It is also known to reinforce the channelmembers by a structural member extending beneath and welded to thebottom surface of the central web of the channel.

As is well known, the prior art nailable steel floorings have generallyhad relatively low friction load support surfaces, which surfaces tendto become more slippery with use as a result of the polishing effect ofarticles being moved over the surface during normal use. This slipperycondition of the floors is accentuated by foreign matter such as oils,water and other liquids or fine solids such as grains, sand, granular orpelletized chemicals or the like which are frequently spilled on thefloor. This slippery condition not only increases the loads placed onthe nails driven into the nailing grooves to anchor the individualarticles for shipping, but also presents a substantial hazard topersonnel loading and unloading the cars and can make it difficult tomaneuver material handling equipment such as forklift trucks or the likecommonly used in loading and unloading cars.

Attempts have been made to provide an anti-skid surface on nailablesteel flooring planks, but the prior art attempts have not been entirelysatisfactory and are not widely used. One such prior art system is shownin U.S. Pat. No. 2,670,060 which discloses the concept of providing ananti-skid surface on a nailable steel flooring plank by forming a seriesof transversly extending channel-like depressions in the top of theflooring planks to structurally reinforce the web of the channel, andthen filling the depressions with a resilient anti-skid material. Whilethis material is effective in providing a less slippery surface for loadhandling equipment and personnel, it has limited effect on heavy, rigidarticles which are supported primarily by the metal surface as on metalbases, wooden pallets, skids or the like.

It is also known to apply an anti-skid metal sheathing to the loadbearing surface of non-metal floors, for example wooden floors, one suchsystem being shown in U.S. Pat. No. 3,365,221. The metal sheathingdisclosed in this patent has a number of circular openings formed by apunching operation which results in the periphery of the openings havingsharp, upturned edges which provide the anti-skid feature of thesurface. Articles may be secured to the wooden floor beneath thesheathing by nails driven through the circular openings. The sheathingis secured to the wooden floors by spikes struck from the metal plateused to form the sheathing.

Anti-skid surfaces are also commonly provided on metal plate membersemployed as walkways, stair treads, catwalks, ladder rungs, balconies,and the like. Such known anti-skid surfaces include raised portionsformed in a continuous pattern on one surface of metal plate, opengratings such as expanded metal, and patterns formed by rupturing and/ordeforming segments of an original smooth, flat metal plate. Anti-skidpanel formed by the later method is disclosed in U.S. Pat. No. 3,093,216in which relatively thin gauge flat metal plate is initially providedwith a series of parallel strengthening ribs, with rows of conical,sharp edged openings formed between the ribs. The ribs are of a heightto enable trucks to roll therealong without being bumped by the conical,perforated anti-skid bumps, or openings. After the ribs and perforationsare formed in the respective plates, the edges are turned under to forma channel shaped panel.

The relatively heavy gauge metal required to provide the strength anddamage resistance required in a railway car floor, and the high speedprecision forming techniques required for commercial production ofnailable steel floor planking members, make it impractical tomanufacture such planking members from sheet stock having anti-skidelements performed on its surface. Such commercial production techniquesrequire the main channel element of the planking members to becontinuously roll formed from strip stock supplied to the formingapparatus in large coils. The strip is unwound and passed throughstraightening rolls before being passed to and through a series of pairsof forming rolls to be progressively roll formed to the channelconfiguration. Accurate control of the forming operation is necessary inorder to provide the necessary close tolerances on the nailing grooveprovided between adjacent planking members in a flooring assembly. Thisgroove must be of sufficient width to permit the driving of nails intothe groove with the nail following the compound-curve configuration ofthe channel flanges and with the spacing of the flanges being such as toprovide the necessary degree of frictional resistance to withdraw thenail to enable heavy freight articles to be firmly secured in positionon the floor. The rolling operation necessarily requires firm contactbetween the forming rolls and the flat surface of the strip stock beingrolled into the planking channel.

SUMMARY OF THE INVENTION

It is the primary object of the present invention to provide a methodfor high speed continuous forming of improved nailable steel floorplanking members, having an improved anti-skid surface thereon, fromcoiled strip steel stock.

Another object of the invention is to provide an improved nailable steelfloor planking member having an anti-skid load bearing surfaceintegrally formed thereon.

In the attainment of the foregoing and other objects and advantages, animportant feature of the invention resides in the die-forming of auniform pattern of anti-skid elements projecting upwardly from the loadbearing surface of the nailable steel floor plank members, with theanti-skid elements having substantially flat top surfaces extendingessentially parallel to the load bearing surface of the planking elementand having side edges extending substantially normal to the surface ofthe planking element to provide improved anti-skid features. Theanti-skid elements may be in the form of short, substantiallycylindrical button-like projections formed on the top surface of theplanking member from metal which is cold formed from the body of theplanking element by a die-forming operation after the flat sheet stockused to form the channel of the planking member has passed through thestraightening rolls and through at least a portion of the forming rolls.The anti-skid members are preferably formed by a punch and die roll pairdriven in synchronization, with the die roll having a plurality of diecavities formed in its outer periphery and the punch roll having aplurality of raised pressure forming elements on its outer periphery toapply sufficient pressure to the strip stock as it passes between theforming rolls to cause the material in the strip to be cold formed intothe die cavity. This process provides a relatively sharp edge surfacearound the top of the anti-skid members without shearing andconsequently weakening the body of the strip material from which theanti-skid members are formed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and advantages of the invention willbecome more apparent from the detailed description thereof containedhereinbelow, taken in conjunction with the drawings in which:

FIG. 1 is a fragmentary isometric view of a section of a nailable steelfloor formed from the improved floor planking member according to thepresent invention;

FIG. 2 is a top plan view, on a reduced scale, of a planking memberemployed in the floor of FIG. 1;

FIG. 3 is a sectional view taken on line 3--3 of FIG. 2;

FIGS. 4a through 4k are views showing fragments of the series rollforming elements employed to shape flat steel stock into the mainchannel of the nailable steel flooring element, including the formationof the anti-skid surface;

FIG. 5 is an elevation view of two of the die-forming rolls shown inFIG. 4g;

FIG. 6 is an enlarged fragmentary sectional view taken on line 6--6 ofFIG. 5; and

FIG. 7 is an enlarged fragmentary sectional view of the die roll pairsshown in FIG. 4g showing the staggered relation of the die-formingelements on the separate roll pairs.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, only a small fragment of the floor 10 of arail car is shown in FIG. 1 to illustrate the side-by-side relation ofthe plurality of identical planking members, or planks 12 which make upthe floor. The planking members 12 extend transversly of the car and aresupported in conventional manner by a plurality of laterally spaced,longitudinally extending beams or girders 14 of the car frame, only onegirder 14 being shown in FIG. 1. The structure of the car, apart fromthe floor and the single girder 14, is not shown as such structure isconventional and forms no part of the invention.

As shown in FIGS. 1-3, the respective floor planking members 12 arewelded assemblies made up of a large, load supporting channel 16 and asmaller, generally U-shaped reinforcing channel 18, both of which areformed from heavy-gauge rolled steel strip. The channel members 16 aredownwardly open when assembled into a floor, and each includes a centralweb 20 having a top surface 22 which cooperates with the webs ofadjacent channels to define the load bearing surface of the floor 10.The central web 20 of each planking member 12 is supported along itsside edge by a pair of integrally formed side flanges 24, 26, each ofwhich terminates at its bottom edge in an inwardly directed ledge 28adapted to engage and be supported by the girders 14.

The flanges 24 and 26 are each of compound-curve configuration in crosssection, with the flange 24 having an outwardly concave or femalecorrugations 30 extending along its length intermediate the web 20 andthe ledge 28, and the flange 26 having an outwardly convex or malecorrugations 32 which is substantially complementary to the concaveconfiguration of flange 24. The flange 26 is provided with a pluralityof longitudinally spaced apart bridges 34 along its length. Each bridge34 presents a substantially flat external or outwardly directed surface36 located in a plane substantially tangent to the laterally outermostportion of the male corrugations 32 and normal to the plane of the topweb surface 22. The bridges 34 extend throughout substantially the fullheight of the flange 26 so as to bridge the female corrugations 30 whentwo of the planking members are placed in side-by-side relation in afloor 10.

When two planking members 12 are arranged in side-by-side relation in afloor, the male corrugations 32 on the flanges 26 are arranged inopposed, contiguous relation with a female corrugations 30 on a flange24 of the adjacent planking member. The contiguous concave and convexsurfaces are spaced apart by the bridge members 34 to define asubstantially sinuous nailing groove 38 therebetween. The compound curveconfiguration of the opposed surfaces on the adjacent flanges, incombination with the accurate spacing of the planking members by thebridge members 34, provide a nailing groove which at once will permitnails to be driven downwardly therethrough and provides sufficientfrictional resistance to withdrawal of the nails to permit nailingbraces, skids and the like to the floor to avoid freight movement duringshipping. In the assembled relation, the respective planking members arepreferably secured in position by welding the ledges 28 directly to thetop flange of the supporting girders 14, thereby positively retainingthe respective planking members 12 against shifting during use.

The top channels 16 of planking members 12 as thus far described aresubstantially identical to the planking members described in U.S. Pat.No. 2,852,112, which patent is assigned to the Assignee of the presentinvention and reference to which may be had for further description ofthe structure. However, it has been found desirable to reinforce theload supporting web 20 of the planking members intermediate the sideflanges 24, 26 in order to minimize distortion of the surface 22 fromheavy concentrated or impact loads which may be encountered in use. Tothis end, the generally U-shaped channel 18 has the free edges of itsopposed legs 40, 42 rigidly welded to the bottom surface of the web 20to reinforce the web along two spaced lines located one on each side ofthe longitudinal center line of the web and cooperating with the flanges24, 26 to provide support for the web at four positions across the widthof the web. The length of the legs 40, 42 may be such as to position thebottom surface of the web 44 of channel 18 in substantially the sameplane as the bottom surface of the ledges 28 to rest directly upon thetop surface of the girders 14. It has been found, however, that thisconfiguration can result in the planking members 12 not setting squarelyupon the supporting girder either as a result of unevenness of thegirder support flange or to the web 44 being slightly below the ledges28 due to manufacturing tolerances or the like. Accordingly, it ispreferable to intentionally dimension the channel 18 to position thebottom surface of the web 44 slightly above the plane of the ledges 28.In this arrangement, only a slight deflection of the web 20 is requiredto bring the U-shaped reinforcing channel firmly to rest upon thesupporting girder to provide additional support for the floor. Asindicated in FIG. 2, the U-shaped support channel 28 may also beslightly shorter than the top channel 28 to facilitate assembly byautomatic welding machines.

As shown in FIG. 2, each planking member 12 has three longitudinallyextending rows of anti-skid projections 46 extending upwardly from thetop surface 22. One row of the projections 46 is located on thelongitudinal center line of the planking member, with the remaining rowsbeing located one on each side and spaced laterally outward of thecenter row. The outer rows of projections 46 are preferably locatedapproximately 2/3 the distance from the center row to the outerlongitudinal edge of the respective planking members so that, when thefloor is assembled, the distance between adjacent rows of projectionsover the floor is substantially equal. This exact spacing is notcritical, however, and in one embodiment of the floor planking members,the distance between adjacent rows of projections on contiguous plankingmembers is slightly greater than the distance between the rows on theindividual planking member. As seen in FIGS. 2 and 3, the legs 40, 42 ofreinforcing channels 18 are welded to the web 20 in outwardly spacedrelation to the central row of projections 46.

The individual anti-friction projections 46 are preferably ofsubstantially cylindrical configuration, having a top surface 48 whichis generally parallel to the surface 22 and having side edge surfacesgenerally normal to the surface 22. This configuration provides arelatively sharp top edge for the respective projections 46 which, incombination with the substantially vertical side edges of the respectiveprojections, provide an exceptionally effective anti-skid surface.

The individual projections 46 in the respective rows of such projectionsare equally spaced from one another, with the projections in adjacentrows being offset longitudinally of the planking members 12 as shown inFIGS. 1 and 2. This offset relation, in combination with thesubstantially uniform spacing of the rows of projections over the floor,produces an anti-skid pattern consisting of generally diagonallyextending rows of projections across the assembled floor.

In an embodiment of the floor panel assembly in which the channel member20 is formed from 10 gauge rolled steel strip, i.e., a strip having athickness of approximately 0.138", the anti-skid projections 46 have aheight, above the surface 22, of approximately 1/16", or slightly lessthan 1/2 the thickness of the base metal. The individual projections 46are die-formed from the metal of the channel itself as more fullydescribed hereinbelow.

Referring now to FIGS. 4 through 7, the preferred method of forming thechannel member 20 having the anti-skid projections 46 integrally formedthereon from a continuous length of flat rolled steel strip material isillustrated. The strip stock 60 is unrolled from a coil of the material(not shown) and passed through a set of conventional straightening rolls(also not shown) to present a running length of flat straight stock tothe nip of an initial set of forming rolls 62, 64 as shown in FIG. 4a.The rolls 62 and 64 may be segmented as illustrated, with the roll 62consisting of roll segments 62a, 62b and 62c and roll 64 consisting ofroll segments 64a, 64b and 64c. Rolls 62, 64 firmly clamp the centralportion of the strip 60 and perform the first step in forming therespective side edges of the strip into the configuration of the flanges24, 26 and the ledges 28. From the initial forming roll set shown inFIG. 4a, the strip passes successively through five additional sets offorming rolls to progressively form the edge portions of the strip tomore closely conform to the final configuration of the flanges 24, 26and the ledges 28, while firmly clamping the central portion of the webto maintain it in a flat, straight condition. Thus, from rolls 62, 64,the strip passes into the nip of rolls 66, 68 at the second formingstation shown in FIG. 4b then into the nip of the third set of formingrolls 70, 72 shown at FIG. 4c. This continues through the 4th, 5th, and6th forming roll sets shown in FIGS. 4d, 4e and 4f, respectively.

Between the 6th and 7th sets of forming rolls, the strip 60, which nowhas the flanges and ledges substantially formed but deflected from theirfinal position, is passed through the nip of a set of die-forming rollsconsisting of three die rolls 86, 88, 90 supported for rotation inopposed relation one to each of a set of pressure rolls 92, 94, 96 whichcooperate to form the three continuous rows of anti-skid projections 46along the length of the metal strip. Following the die-forming operationillustrated at FIG. 4g, the strip 60 passes successively through fouradditional forming roll sets 98-100, 102-104, 106-108 and 110-112 asshown in FIGS. 4h through 4k. As the strip emerges from the 10th rollforming operation illustrated in FIG. 4k, the channel 16 is completelyformed with the dimensions being accurately controlled throughout theforming operation. Since the forming operations performed in the lastfour sets of forming rolls consist essentially of deflecting or bendingthe substantially formed flange portions of the strip into the finalconfiguration, relatively little transverse stress is applied to the webportion of the strip. For this reason, it is possible to shape theforming roll which engages the top or outer surface of the web portionof the channel with peripheral grooves 114 which permit the anti-skidprojections 46 to pass untouched through the forming roll sets at thefinal four stations.

FIGS. 5 and 6 show the punch roll 94 and the opposed die roll 88 withthe strip 60 passing therebetween to form the center roll of anti-skidprojections 46. As shown, roll 88 has twelve die cavities 116 in itsouter periphery, at equally spaced intervals therearound, whichcooperate with a corresponding member of raised pressure points, orpunches 118 carried on the periphery of the opposing pressure roll 94.As shown in FIG. 6, the individual die cavities 116 are defined by acylindrical sleeve or die member 120 formed from a suitably hardenedmetal and seated within a cylindrical bore 122 within the periphery ofthe wheel 88. The die member 120 is retained within the bore by suitablemeans such as the set screw 124. A bore 126 extending from one side faceof wheel 88 into the bore 122 enables the die member 120 to be drivenfrom its seat by a suitable tool inserted through bore 126 uponloosening the set screw 124.

Die member 120 has a die cavity in the form of a generally cylindricalbore 128 into which the anti-friction projection 46 is formed. Bore 128is actually slightly conical to facilitate withdrawal of the shortanti-friction projection 46 from within the bore 128. In practice, thebore 128 may be tapered at approximately 5°, which taper will readilypermit the anti-friction projection to be withdrawn without damage tothe edge of the projection or to the wall of the die member.Nevertheless, the projections 46 are, for all practical purposes,substantially cylindrical with the side face, or edge of the individualprojections extending substantially normal to the top surface of thestrip 60.

The pressure rolls 92, 94, 96 are each formed with cylindrical recesses130 around their periphery for receiving a cylindrical, hardened pinpressure element 132 which is retained in the recess 130 by a set screw134. Radial bores 136 extend from the bottom of the cylindrical recess130 to the central opening of the respective wheels so that, uponremoval of the wheels from their support shaft 138, a suitable rodmember inserted within the bore 136 can be employed to positively drivethe pressure element 132 from the recess 130.

The individual pressure elements 130 have a substantially sphericalouter end 140 which projects outwardly beyond the peripheral rimportion, or surface of the respective pressure wheel. The diameter ofthe respective pins or pressure elements 132 is substantially greaterthan the diameter of the die bore 128 so that the spherical end portion140 of the pin member applies a compressive force over an areasubstantially greater than the cross-sectional area of the bore 128 ofthe opposed die. However, the total height, or radial projection, of thespherical section 140 is substantially less than the height of theanti-skid projections. This results in the spherical end 140 forming adepression 142 on the bottom surface of the web 20, with the totalvolume of the spherical end depression 142 being substantially equal tothe total volume of the resulting anti-skid projection 46 formed withinthe die element.

By firmly clamping the steel strip 60 between the opposed die rolls, theconcentrated pressure caused by the projecting end 140 of the pin member132 causes a cold flow of the metal into the opposed die cavity 128 sothat the resulting projection 46 substantially conforms to thecross-sectional configuration of the die cavity. By utilizing a coldflow forming process, as opposed to a direct punching operation, themetal within the area of the anti-skid projections of web 20 is notmaterially weakened. This enables the relatively straight sided, shortprojections 46 to withstand substantial shearing force in resistingsliding movement of freight articles supported on the surface of a floorconstructed from the flooring plank members constructed in accordancewith the present invention.

While I have disclosed a preferred embodiment of my invention, I wish itunderstood that I do not intend to be restricted solely thereto, butrather that I intend to include all embodiments thereof which would beapparent to one skilled in the art and which come within the spirit andscope of my invention.

What is claimed is:
 1. In a nailable steel floor construction includingsupport means supporting a plurality of elongated substantiallyidentical floor planking members, the planking members comprising,astructural channel member roll formed from flat steel stock ofsubstantially uniform thickness, the channel member having a central webdefining a substantially flat load bearing surface and first and seconddownwardly depending flange members formed one on each side of thecentral web and each terminating at its lower edge in an inwardly turnedledge, the first flange having a longitudinally extending outwardlyconcave corrugation formed thereon and the second flange having anoutwardly convex corrugation which is substantially complementary to theconcave corrugation on the first flange, spacing means formed on atleast one of the flanges at spaced intervals therealong for engaging theflange on an adjacent planking member in the floor construction toprovide a nailing groove therebetween when the planking members areassembled into a floor, an elongated substantially U-shaped reinforcingchannel rigidly welded to the central web between the flanges andextending substantially the full length of the structural channel, thereinforcing channel having a base web disposed in a plane substantiallyparallel to the plane of the ledges on the first and second flanges andspaced slightly therefrom in the direction of said central web andupwardly extending legs formed one on each side edge of the base web andterminating in parallel spaced edges, the free edges being rigidlywelded to the central web one on each side of the longitudinal centerline thereof, and a plurality of anti-skid projections of generallycylindrical configuration integrally formed on and projecting outwardlyfrom the load bearing surface of the central web, the anti-skidprojections being die pressed from the material of the flat steel stocklocated in substantially parallel rows extending longitudinally of thestructural channel, the anti-skid projections each having a top surfaceextending generally parallel to and spaced from the load bearing surfaceof the central web and side edges extending substantially perpendicularto the load support surface of the central web, said top surface andsaid side edges intersecting at an angle to provide an abrupt,relatively sharp top peripheral edge on the anti-skid projections. 2.The invention as defined in claim 1 wherein said anti-skid projectionshave a height above the load bearing surface of the central web which isno greater than about half the thickness of the central web.
 3. Theinvention as defined in claim 1 wherein said anti-skid projections areformed in three laterally spaced apart, parallel rows and where one ofsaid rows is located substantially on the longitudinal center line ofthe central web.
 4. The invention as defined in claim 1 wherein theanti-skid projections in each row are equally spaced from one anotherand wherein the projections in the respective rows are offset from oneanother by substantially equal amounts to provide substantiallydiagonally extending rows of anti-skid projections in a floorconstructed by a plurality of said planking members arranged inside-by-side relation.